Design of the PET–MR system for head imaging of the DREAM Project

NOTICE: this is the author’s version of a work that was accepted for publication in Nuclear Instruments and Methods in Physics Research Section A. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Nuclear Instruments and Methods in Physics Research Section A, Volume 702, 21 February 2013, Pages 94–97 DOI 10.1016/j.nima.2012.08.028In this paper we describe the overall design of a PET–MR system for head imaging within the framework of the DREAM Project as well as the first detector module tests. The PET system design consists of 4 rings of 16 detector modules each and it is expected to be integrated in a head dedicated radio frequency coil of an MR scanner. The PET modules are based on monolithic LYSO crystals coupled by means of optical devices to an array of 256 Silicon Photomultipliers. These types of crystals allow to preserve the scintillation light distribution and, thus, to recover the exact photon impact position with the proper characterization of such a distribution. Every module contains 4 Application Specific Integrated Circuits (ASICs) which return detailed information of several light statistical momenta. The preliminary tests carried out on this design and controlled by means of ASICs have shown promising results towards the suitability of hybrid PET–MR systems.This work was supported by the Centre for Industrial Technological Development co-funded by FEDER through the Technology Fund (DREAM Project, IDI-20110718), the Spanish Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica (I + D + I) under Grant no. FIS2010-21216-CO2-01 and the Valencian Local Government under Grant PROMETEO 2008/114.González Martínez, AJ.; Conde, P.; Hernández Hernández, L.; Herrero Bosch, V.; Moliner Martínez, L.; Monzó Ferrer, JM.; Orero Palomares, A.... (2013). Design of the PET–MR system for head imaging of the DREAM Project. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 702:94-97. https://doi.org/10.1016/j.nima.2012.08.028S949770

Implementation and analysis of list mode algorithm using tubes of response on a dedicated brain and breast PET

In this work we present an innovative algorithm for the reconstruction of PET images based on the List-Mode (LM) technique which improves their spatial resolution compared to results obtained with current MLEM algorithms. This study appears as a part of a large project with the aim of improving diagnosis in early Alzheimer disease stages by means of a newly developed hybrid PET-MR insert. At the present, Alzheimer is the most relevant neurodegenerative disease and the best way to apply an effective treatment is its early diagnosis. The PET device will consist of several monolithic LYSO crystals coupled to SiPM detectors. Monolithic crystals can reduce scanner costs with the advantage to enable implementation of very small virtual pixels in their geometry. This is especially useful for LM reconstruction algorithms, since they do not need a pre-calculated system matrix. We have developed an LM algorithm which has been initially tested with a large aperture (186 mm) breast PET system. Such an algorithm instead of using the common lines of response, incorporates a novel calculation of tubes of response. The new approach improves the volumetric spatial resolution about a factor 2 at the border of the field of view when compared with traditionally used MLEM algorithm. Moreover, it has also shown to decrease the image noise, thus increasing the image quality. © 2012 Elsevier B.V. All rights reserved.This work was supported by the Centre for Industrial Technological Development co-funded by FEDER through the Technology Fund (DREAM Project, IDI-20110718), by the Spanish Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica (I+D+I) under Grant. No. FIS2010-21216-CO2-01TEO 2008/114.Moliner Martínez, L.; Correcher, C.; González Martínez, AJ.; Conde Castellanos, PE.; Hernández Hernández, L.; Orero Palomares, A.; Rodríguez Álvarez, MJ.... (2013). Implementation and analysis of list mode algorithm using tubes of response on a dedicated brain and breast PET. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 702:129-132. https://doi.org/10.1016/j.nima.2012.08.029S12913270

Monolithic crystals for PET devices: optical coupling optimization

NOTICE: this is the author’s version of a work that was accepted for publication in Nuclear Instruments and Methods in Physics Research Section A. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Nuclear Instruments and Methods in Physics Research Section A [Volume 731, 11 December 2013, Pages 288–294] DOI 10.1016/j.nima.2013.05.049[EN] In this work we present a method to efficiently collect scintillation light when using monolithic scintillator crystals. The acceptance angle of the scintillation light has been reduced by means of optical devices reducing the border effect which typically affects continuous crystals. We have applied this procedure on gamma detectors for PET systems using both position sensitive PMTs and arrays of SiPMs. In the case of using SiPMs, this approach also helps to reduce the photosensor active area. We evaluated the method using PMTs with a variety of different crystals with thicknesses ranging from 10 to 24 mm. We found that our design allows the use of crystal blocks with a thickness of up to 18 mm without degrading the spatial resolution caused by edge effects and without a significant detriment to the energy resolution. These results were compared with simulated data. The first results of monolithic LYSO crystals coupled to an array of 256 SiPMs by means of individual optical light guides are also presented.This work was supported by the Centre for Industrial Technological Development co-funded by FEDER through the Technology Fund (DREAM Project, IDI-20110718), the Spanish Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica (I+D +I) under Grant no. FIS2010-21216-CO2-01 and the Valencian Local Government under Grant PROMETEO 2008/114.González Martínez, AJ.; Peiró, A.; Conde, P.; Hernández Hernández, L.; Moliner Martínez, L.; Orero Palomares, A.; Rodríguez-Álvarez, M.... (2013). Monolithic crystals for PET devices: optical coupling optimization. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 731:288-294. https://doi.org/10.1016/j.nima.2013.05.049S28829473

Building blocks of a multi-layer PET with time sequence photon interaction discrimination and double Compton camera

[EN] Current PET detectors have a very low sensitivity, of the order of a few percent. One of the reasons is the fact that Compton interactions are rejected. If an event involves multiple Compton scattering and the total deposited energy lays within the photoelectric peak, then an energy-weighted centroid is the given output for the coordinates of the reconstructed interaction point. This introduces distortion in the final reconstructed image. The aim of our work is to prove that Compton events are a very rich source of additional information as one can improve the resolution of the detector and implicitly the final reconstructed image. This could be a real breakthrough for PET detector technology as one should be able to obtain better results with less patient radiation. Using a PET as a double Compton camera, by means of Compton cone matching i.e., Compton cones coming from the same event should be compatible, is applied to discard randoms, patient scattered events and also, to perform a correct matching among events with multiple coincidences. In order to fully benefit experimentally from Compton events using monolithic scintillators a multi-layer configuration is needed and a good time-of-flight resolution.This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 695536). This work was supported in part by the Spanish Government Grants TEC2016-79884-C2 and RTC-2016-5186-1.Ilisie, V.; Giménez-Alventosa, V.; Moliner Martínez, L.; Sánchez, F.; González Martínez, AJ.; Rodríguez-Álvarez, M.; Benlloch Baviera, JM. (2018). Building blocks of a multi-layer PET with time sequence photon interaction discrimination and double Compton camera. Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment. 895:74-83. https://doi.org/10.1016/j.nima.2018.03.076S748389

Dependence of polytetrafluoroethylene reflectance on thickness at visible and ultraviolet wavelengths in air

[EN] Polytetrafluoroethylene (PTFE) is an excellent diffuse reflector widely used in light collection systems for particle physics experiments. However, the reflectance of PTFE is a function of its thickness. In this work, we investigate this dependence in air for light of wavelengths 260 nm and 450 nm using two complementary methods. We find that PTFE reflectance for thicknesses from 5 mm to 10 mm ranges from 92.5% to 94.5% at 450 nm, and from 90.0% to 92.0% at 260 nm We also see that the reflectance of PIFE of a given thickness can vary by as much as 2.7% within the same piece of material. Finally, we show that placing a specular reflector behind the PTFE can recover the loss of reflectance in the visible without introducing a specular component in the reflectance.The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787-NEXT; the European Union's Framework Programme for Research and Innovation Horizon 2020 (2014-2020) under the Grant Agreements No. 674896, 690575 and 740055; the Ministerio de Economia y Competitividad and the Ministerio de Ciencia, Innovacion y Universidades of Spain under grants FIS2014-53371-C04, RTI2018-095979, the Severo Ochoa Program grants SEV-2014-0398 and CEX2018-000867-S, and the Maria de Maeztu Program MDM-2016-0692; the Generalitat Valenciana under grants PROMETEO/2016/120 and SEJI/2017/011; the Portuguese FCT under project PTDC/FIS-NUC/2525/2014 and under projects UID/04559/2020 to fund the activities of LIBPhys-UC; the U.S. Department of Energy under contracts No. DE-AC02-06CH11357 (Argonne National Laboratory), DE-AC0207CH11359 (Fermi National Accelerator Laboratory), DE-FG02-13ER42020 (Texas A&M) and DE-SC0019223/DE-SC0019054 (University of Texas at Arlington); and the University of Texas at Arlington (USA). DGD acknowledges Ramon y Cajal program (Spain) under contract number RYC2015-18820. JM-A acknowledges support from Fundacion Bancaria "la Caixa" (ID 100010434), grant code LCF/BQ/PI19/11690012. Finally, we thank Brendon Bullard, Paolo Giromini and Neeraj Tata for helpful discussions and assistance with preliminary measurements.Ghosh, S.; Haefner, J.; Martín-Albo, J.; Guenette, R.; Li, X.; Loya Villalpando, A.; Burch, C.... (2020). Dependence of polytetrafluoroethylene reflectance on thickness at visible and ultraviolet wavelengths in air. Journal of Instrumentation. 15(11):1-17. https://doi.org/10.1088/1748-0221/15/11/P11031S1171511Auger, M., Auty, D. J., Barbeau, P. S., Bartoszek, L., Baussan, E., Beauchamp, E., … Cleveland, B. (2012). The EXO-200 detector, part I: detector design and construction. Journal of Instrumentation, 7(05), P05010-P05010. doi:10.1088/1748-0221/7/05/p05010Martín-Albo, J., Muñoz Vidal, J., Ferrario, P., Nebot-Guinot, M., Gómez-Cadenas, J. J., … Cárcel, S. (2016). Sensitivity of NEXT-100 to neutrinoless double beta decay. Journal of High Energy Physics, 2016(5). doi:10.1007/jhep05(2016)159Rogers, L., Clark, R. A., Jones, B. J. P., McDonald, A. D., Nygren, D. R., Psihas, F., … Azevedo, C. D. . (2018). High voltage insulation and gas absorption of polymers in high pressure argon and xenon gases. Journal of Instrumentation, 13(10), P10002-P10002. doi:10.1088/1748-0221/13/10/p10002Silva, C., Pinto da Cunha, J., Pereira, A., Chepel, V., Lopes, M. I., Solovov, V., & Neves, F. (2010). Reflectance of polytetrafluoroethylene for xenon scintillation light. Journal of Applied Physics, 107(6), 064902. doi:10.1063/1.3318681Haefner, J., Neff, A., Arthurs, M., Batista, E., Morton, D., Okunawo, M., … Lorenzon, W. (2017). Reflectance dependence of polytetrafluoroethylene on thickness for xenon scintillation light. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 856, 86-91. doi:10.1016/j.nima.2017.01.057Kravitz, S., Smith, R. J., Hagaman, L., Bernard, E. P., McKinsey, D. N., Rudd, L., … Sakai, M. (2020). Measurements of angle-resolved reflectivity of PTFE in liquid xenon with IBEX. The European Physical Journal C, 80(3). doi:10.1140/epjc/s10052-020-7800-6Geis, C., Grignon, C., Oberlack, U., García, D. R., & Weitzel, Q. (2017). Optical response of highly reflective film used in the water Cherenkov muon veto of the XENON1T dark matter experiment. Journal of Instrumentation, 12(06), P06017-P06017. doi:10.1088/1748-0221/12/06/p06017Allison, J., Amako, K., Apostolakis, J., Arce, P., Asai, M., Aso, T., … Barrand, G. (2016). Recent developments in Geant4. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 835, 186-225. doi:10.1016/j.nima.2016.06.12

PADC nuclear track detector for ion spectroscopy in laser-plasma acceleration

[EN] The transparent polymer polyallyl-diglycol-carbonate (PADC), also known as CR-39, is widely used as detector for heavy charged particles at low fluence. It allows for detection of single protons and ions via formation of microscopic tracks after etching in NaOH or KOH solutions. PADC combines a high sensitivity and high specificity with inertness towards electromagnetic noise. Present fields of application include laser-ion acceleration, inertial confinement fusion, radiobiological studies with cell cultures, and dosimetry of nuclear fragments in particle therapy. These require precise knowledge of the energy-dependent response of PADC to different ion species. We present calibration data for a new type of detector material, Radosys RS39, to protons (0.2-3 MeV) and carbon ions (0.6-12 MeV). RS39 is less sensitive to protons than other types of PADC. Its response to carbon ions, however, is similar to other materials. Our data indicate that RS39 allows for measuring carbon ion energies up to 10 MeV only from the track diameters. In addition, it can be used for discrimination between protons and carbon ions in a single etching process.Project funded by CSIC, Grant No. 2018501082, and by the Spanish Ministerio de Ciencia, Innovacion y Universidades, project MdM-2016-0692-17-2 via a predoctoral grant of type Maria de Maeztu FPI. Nuclear track detector material and readout equipment have been provided by Radosys Ldt. (Budapest). The authors acknowledge the contributions and commitment of the CNA accelerator operators. MS would like to thank L. Ballesteros and J. Ortiz for their support with precision equipment.Seimetz, M.; Peñas, J.; Llerena, JJ.; Benlliure, J.; García López, J.; Millán-Callado, MA.; Benlloch Baviera, JM. (2020). PADC nuclear track detector for ion spectroscopy in laser-plasma acceleration. Physica Medica. 76:72-76. https://doi.org/10.1016/j.ejmp.2020.06.005S727676Kodaira, S., Kitamura, H., Kurano, M., Kawashima, H., & Benton, E. R. (2019). Contribution to dose in healthy tissue from secondary target fragments in therapeutic proton, He and C beams measured with CR-39 plastic nuclear track detectors. Scientific Reports, 9(1). doi:10.1038/s41598-019-39598-0Scampoli, P., Casale, M., Durante, M., Grossi, G., Pugliese, M., & Gialanella, G. (2001). Low-energy light ion irradiation beam-line for radiobiological studies. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 174(3), 337-343. doi:10.1016/s0168-583x(00)00622-4WADA, S., KOBAYASHI, Y., FUNAYAMA, T., NATSUHORI, M., ITO, N., & YAMAMOTO, K. (2002). Detection of DNA Damage in Individual Cells Induced by Heavy-ion Irradiation with an Non-denaturing Comet Assay. Journal of Radiation Research, 43(S), S153-S156. doi:10.1269/jrr.43.s153Gaillard, S., Pusset, D., de Toledo, S. M., Azzam, E. I., & Fromm, M. (2008). Distance distribution of bystander effects in alpha-particle irradiated cell populations using a CR-39-based culture dish. Radiation Measurements, 43, S34-S40. doi:10.1016/j.radmeas.2008.03.063Yogo, A., Maeda, T., Hori, T., Sakaki, H., Ogura, K., Nishiuchi, M., … Kondo, K. (2011). Measurement of relative biological effectiveness of protons in human cancer cells using a laser-driven quasimonoenergetic proton beamline. Applied Physics Letters, 98(5), 053701. doi:10.1063/1.3551623Séguin, F. H., Frenje, J. A., Li, C. K., Hicks, D. G., Kurebayashi, S., Rygg, J. R., … Padalino, S. (2003). Spectrometry of charged particles from inertial-confinement-fusion plasmas. Review of Scientific Instruments, 74(2), 975-995. doi:10.1063/1.1518141Daido, H., Nishiuchi, M., & Pirozhkov, A. S. (2012). Review of laser-driven ion sources and their applications. Reports on Progress in Physics, 75(5), 056401. doi:10.1088/0034-4885/75/5/056401Sinenian, N., Rosenberg, M. J., Manuel, M., McDuffee, S. C., Casey, D. T., Zylstra, A. B., … Petrasso, R. D. (2011). The response of CR-39 nuclear track detector to 1–9 MeV protons. Review of Scientific Instruments, 82(10), 103303. doi:10.1063/1.3653549Malinowska A, Szydłowski A, Jaskóła M, Korman A, Sartowska B, Kuehn T, Kuk M. Investigations of protons passing through the CR-39/PM-355 type of solid state nuclear track detectors, Rev Sci Instrum 84 (2013) 073511.Baccou, C., Yahia, V., Depierreux, S., Neuville, C., Goyon, C., Consoli, F., … Labaune, C. (2015). CR-39 track detector calibration for H, He, and C ions from 0.1-0.5 MeV up to 5 MeV for laser-induced nuclear fusion product identification. Review of Scientific Instruments, 86(8), 083307. doi:10.1063/1.4927684Seimetz, M., Bellido, P., García, P., Mur, P., Iborra, A., Soriano, A., … Benlloch, J. M. (2018). Spectral characterization of laser-accelerated protons with CR-39 nuclear track detector. Review of Scientific Instruments, 89(2), 023302. doi:10.1063/1.5009587Xiaojiao, D., Xiaofei, L., Zhixin, T., Yongsheng, H., Shilun, G., Dawei, Y., & Naiyan, W. (2009). Calibration of CR-39 with monoenergetic protons. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 609(2-3), 190-193. doi:10.1016/j.nima.2009.08.061Kodaira, S., Morishige, K., Kawashima, H., Kitamura, H., Kurano, M., Hasebe, N., … Ogura, K. (2016). A performance test of a new high-surface-quality and high-sensitivity CR-39 plastic nuclear track detector – TechnoTrak. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 383, 129-135. doi:10.1016/j.nimb.2016.07.002Ogura, K., Asano, M., Yasuda, N., & Yoshida, M. (2001). Properties of TNF-1 track etch detector. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 185(1-4), 222-227. doi:10.1016/s0168-583x(01)00816-3Malinowska, A., Jaskóła, M., Korman, A., Szydłowski, A., & Kuk, M. (2014). Characterization of solid state nuclear track detectors of the polyallyl-diglycol-carbonate (CR-39/PM-355) type for light charged particle spectroscopy. Review of Scientific Instruments, 85(12), 123505. doi:10.1063/1.4903755Bahrami, F., Mianji, F., Faghihi, R., Taheri, M., & Ansarinejad, A. (2016). Response of CR-39 to 0.9–2.5 MeV protons for KOH and NaOH etching solutions. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 813, 96-101. doi:10.1016/j.nima.2016.01.015Jeong, T. W., Singh, P. K., Scullion, C., Ahmed, H., Hadjisolomou, P., Jeon, C., … Ter-Avetisyan, S. (2017). CR-39 track detector for multi-MeV ion spectroscopy. Scientific Reports, 7(1). doi:10.1038/s41598-017-02331-wKanasaki, M., Hattori, A., Sakaki, H., Fukuda, Y., Yogo, A., Jinno, S., … Yamauchi, T. (2013). A high energy component of the intense laser-accelerated proton beams detected by stacked CR-39. Radiation Measurements, 50, 46-49. doi:10.1016/j.radmeas.2012.10.009Groza, A., Serbanescu, M., Butoi, B., Stancu, E., Straticiuc, M., Burducea, I., … Ganciu, M. (2019). Advances in Spectral Distribution Assessment of Laser Accelerated Protons using Multilayer CR-39 Detectors. Applied Sciences, 9(10), 2052. doi:10.3390/app9102052Zhang, Y., Wang, H.-W., Ma, Y.-G., Liu, L.-X., Cao, X.-G., Fan, G.-T., … Fang, D.-Q. (2019). Energy calibration of a CR-39 nuclear-track detector irradiated by charged particles. Nuclear Science and Techniques, 30(6). doi:10.1007/s41365-019-0619-xSeimetz, M., Bellido, P., Soriano, A., Garcia Lopez, J., Jimenez-Ramos, M. C., Fernandez, B., … Benlloch, J. M. (2015). Calibration and Performance Tests of Detectors for Laser-Accelerated Protons. IEEE Transactions on Nuclear Science, 62(6), 3216-3224. doi:10.1109/tns.2015.2480682Rana, M. A., & Qureshi, I. . (2002). Studies of CR-39 etch rates. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 198(3-4), 129-134. doi:10.1016/s0168-583x(02)01526-4Hermsdorf, D., Hunger, M., Starke, S., & Weickert, F. (2007). Measurement of bulk etch rates for poly-allyl-diglycol carbonate (PADC) and cellulose nitrate in a broad range of concentration and temperature of NaOH etching solution. Radiation Measurements, 42(1), 1-7. doi:10.1016/j.radmeas.2006.06.009Azooz, A. A., & Al-Jubbori, M. A. (2013). Interrelated temperature dependence of bulk etch rate and track length saturation time in CR-39 detector. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 316, 171-175. doi:10.1016/j.nimb.2013.09.001Jadrníčková I, Spurný F. To the spectrometry of linear energy transfer in charged particle beams by means of track-etch detectors, Radiat Measure 43(2008): S191–S194, proceedings of the 23rd International Conference on Nuclear Tracks in Solids. doi: 10.1016/j.radmeas.2008.04.010.Sadowski, M., Al-Mashhadani, E. M., Szydłowski, A., Czyzewski, T., Głowacka, L., Jaskóła, M., … Wieluński, M. (1995). Comparison of responses of CR-39 and PM-355 track detectors to fast protons, deuterons and 4He ions within energy range 0.2–4.5 MeV. Radiation Measurements, 25(1-4), 175-176. doi:10.1016/1350-4487(95)00066-nSadowski, M., Szydlowski, A., Jaskola, M., Czyzewski, T., & Kobzev, A. P. (1997). Comparison of responses of CR-39, PM-355, and CN track detectors to energetic hydrogen-, helium-, nitrogen-, and oxygen-ions. Radiation Measurements, 28(1-6), 207-210. doi:10.1016/s1350-4487(97)00069-3Henig, A., Steinke, S., Schnürer, M., Sokollik, T., Hörlein, R., Kiefer, D., … Habs, D. (2009). Radiation-Pressure Acceleration of Ion Beams Driven by Circularly Polarized Laser Pulses. Physical Review Letters, 103(24). doi:10.1103/physrevlett.103.245003Kar, S., Kakolee, K. F., Qiao, B., Macchi, A., Cerchez, M., Doria, D., … Borghesi, M. (2012). Ion Acceleration in Multispecies Targets Driven by Intense Laser Radiation Pressure. Physical Review Letters, 109(18). doi:10.1103/physrevlett.109.185006Palaniyappan, S., Huang, C., Gautier, D. C., Hamilton, C. E., Santiago, M. A., Kreuzer, C., … Fernández, J. C. (2015). Efficient quasi-monoenergetic ion beams from laser-driven relativistic plasmas. Nature Communications, 6(1). doi:10.1038/ncomms10170McGuffey, C., Raymond, A., Batson, T., Hua, R., Petrov, G. M., Kim, J., … Beg, F. N. (2016). Acceleration of high charge-state target ions in high-intensity laser interactions with sub-micron targets. New Journal of Physics, 18(11), 113032. doi:10.1088/1367-2630/18/11/113032Ma, W. J., Kim, I. J., Yu, J. Q., Choi, I. W., Singh, P. K., Lee, H. W., … Nam, C. H. (2019). Laser Acceleration of Highly Energetic Carbon Ions Using a Double-Layer Target Composed of Slightly Underdense Plasma and Ultrathin Foil. Physical Review Letters, 122(1). doi:10.1103/physrevlett.122.014803Hegelich, M., Karsch, S., Pretzler, G., Habs, D., Witte, K., Guenther, W., … Roth, M. (2002). MeV Ion Jets from Short-Pulse-Laser Interaction with Thin Foils. Physical Review Letters, 89(8). doi:10.1103/physrevlett.89.085002Henig, A., Kiefer, D., Markey, K., Gautier, D. C., Flippo, K. A., Letzring, S., … Hegelich, B. M. (2009). Enhanced Laser-Driven Ion Acceleration in the Relativistic Transparency Regime. Physical Review Letters, 103(4). doi:10.1103/physrevlett.103.045002Carroll, D. C., Tresca, O., Prasad, R., Romagnani, L., Foster, P. S., Gallegos, P., … McKenna, P. (2010). Carbon ion acceleration from thin foil targets irradiated by ultrahigh-contrast, ultraintense laser pulses. New Journal of Physics, 12(4), 045020. doi:10.1088/1367-2630/12/4/045020Jung, D., Yin, L., Albright, B. J., Gautier, D. C., Letzring, S., Dromey, B., … Hegelich, B. M. (2013). Efficient carbon ion beam generation from laser-driven volume acceleration. New Journal of Physics, 15(2), 023007. doi:10.1088/1367-2630/15/2/023007Dollar, F., Zulick, C., Matsuoka, T., McGuffey, C., Bulanov, S. S., Chvykov, V., … Krushelnick, K. (2013). High contrast ion acceleration at intensities exceeding 1021 Wcm−2. Physics of Plasmas, 20(5), 056703. doi:10.1063/1.4803082Kohno, R., Yasuda, N., Takeshi, H., Kase, Y., Ochiai, K., Komori, M., … Kanai, T. (2005). Measurements of Dose-Averaged Linear Energy Transfer Distributions in Water Using CR-39 Plastic Nuclear Track Detector for Therapeutic Carbon Ion Beams. Japanese Journal of Applied Physics, 44(12), 8722-8726. doi:10.1143/jjap.44.8722Romo, V., Rickards, J., Espinosa, G., & Golzarri, J. I. (1999). The Response of CR-39 Polycarbonate to Energetic Carbon Ions. Radiation Protection Dosimetry, 85(1), 459-461. doi:10.1093/oxfordjournals.rpd.a032897Szydlowski, A., Czyzewski, T., Jaskola, M., Sadowski, M., Korman, A., Kedzierski, J., & Kretschmer, W. (1999). Investigation of response of CR-39, PM-355 and PM-500 types of nuclear track detectors to energetic carbon ions. Radiation Measurements, 31(1-6), 257-260. doi:10.1016/s1350-4487(99)00125-

Expectation maximization (EM) algorithms using polar symmetriesfor computed tomography(CT) image reconstruction

We suggest a symmetric-polar pixellation scheme which makes possible a reduction of the computational cost for expectation maximization (EM) iterative algorithms. The proposed symmetric-polar pixellation allows us to deal with 3D images as a whole problem without dividing the 3D problem into 2D slices approach. Performance evaluation of each approach in terms of stability and image quality is presented. Exhaustive comparisons between all approaches were conducted in a 2D based image reconstruction model. From these 2D approaches, that showing the best performances were finally implemented and evaluated in a 3D based image reconstruction model. Comparison to 3D images reconstructed with FBP is also presented. Although the algorithm is presented in the context of computed tomography (CT) image reconstruction, it can be applied to any other tomographic technique as well, due to the fact that the only requirement is a scanning geometry involving measurements of an object under different projection angles. Real data have been acquired with a small animal (CT) scanner to verify the proposed mathematical description of the CT system.This work was supported by the Spanish Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica (I+D+I) under Grant, FIS2010-21216-CO2-01, Valencian Local Government under Grant Nos. PROMETEO 2008/114 and APOSTD/2010/012. The authors would like to thank Brennan Holt for checking and correcting the text.Rodríguez Álvarez, MJ.; Soriano Asensi, A.; Iborra Carreres, A.; Sánchez Martínez, F.; González Martínez, AJ.; Conde, P.; Hernández Hernández, L.... (2013). Expectation maximization (EM) algorithms using polar symmetriesfor computed tomography(CT) image reconstruction. Computers in Biology and Medicine. 43(8):1053-1061. https://doi.org/10.1016/j.compbiomed.2013.04.015S1053106143

Low-diffusion Xe-He gas mixtures for rare-event detection: electroluminescence yield

High pressure xenon Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification are being proposed for rare event detection such as directional dark matter, double electron capture and double beta decay detection. The discrimination of the rare event through the topological signature of primary ionisation trails is a major asset for this type of TPC when compared to single liquid or double-phase TPCs, limited mainly by the high electron diffusion in pure xenon. Helium admixtures with xenon can be an attractive solution to reduce the electron diffu- sion significantly, improving the discrimination efficiency of these optical TPCs. We have measured the electroluminescence (EL) yield of Xe–He mixtures, in the range of 0 to 30% He and demonstrated the small impact on the EL yield of the addition of helium to pure xenon. For a typical reduced electric field of 2.5 kV/cm/bar in the EL region, the EL yield is lowered by ∼ 2%, 3%, 6% and 10% for 10%, 15%, 20% and 30% of helium concentration, respectively. This decrease is less than what has been obtained from the most recent simulation framework in the literature. The impact of the addition of helium on EL statistical fluctuations is negligible, within the experimental uncertainties. The present results are an important benchmark for the simulation tools to be applied to future optical TPCs based on Xe-He mixtures. [Figure not available: see fulltext.]